Diadenosine tetraphosphate and derivatives thereof have various physiological activities, such as stimulation of DNA synthesis in G.sub.1 -arrested baby hamster kidney (BHK) cells (F. Grummt, Proc. Natl; Acad. Sci. USA, Vol. 75, p.371 (1978)), inhibition of phosphorylation of immunoglobulin G (P.F. Maness et al., J. Biol. Chem., Vol.258 p.4055 (1983)), and inhibition of blood-platelet aggregation by adenosine diphosphate (M.J. Harrison et al., FEBS Letters, Vol.54, p.57 (1975)). Because of these activities, diadenosine tetraphosphates and derivatives thereof has been developed as being a substance which is hoped to be suitable for use as medicines such as an antithrombogenic agent, a thrombus preventing agent, etc., and starting materials for their production.
Methods for preparing diadenosine tetraphosphate (hereinafter collectively referred to as A.sub.p4 A) and derivatives thereof have been reported by O. Goerlich et al in Eur. J. Biochem., Vol.126, p.135 (1982): in the presence of various aminoacyl-tRNA synthetases such as E. coli lysyl-tRNA synthetase, histidyl-tRNA synthetase, phenylalanyl-tRNA synthetase, yeast lysyl-tRNA synthetase, phenylalanyl-tRNA synthetase, Fusarium phenylalanyl-tRNA synthetase, and phenylalanyl-tRNA synthetase from sheep liver cells, diadenosine tetraphosphate can be synthesized from adenosine-5'-triphosphate (hereinafter referred to as ATP), and dideoxyadenosine tetraphosphate, which is a derivative of diadenosine tetraphosphate can be synthesized from an ATP derivative, 2'-deoxyadenosine-5'-triphosphate.
The major disadvantage of this method which consists of reacting ATP or derivatives thereof (hereinafter referred to as NTP) with amino acids in the presence of aminoacyl-tRNA synthetases is that in addition to the desired A.sub.p4 A or derivatives thereof, diadenosine triphosphate (hereinafter referred to as A.sub.p3 A) or derivatives thereof, adenosine-5'-diphosphate (ADP) or derivatives thereof (hereinafter referred to as NDP), and adenosine-5'-monophosphate (AMP) or derivatives thereof (hereinafter referred to as NMP) are formed as by-products. Formation of such by-products results in an uneconomical use of the expensive starting material NTP and leads to a lower yield of A.sub.P4 A or derivatives thereof. Furthermore, it is extremely difficult to separate the desired A.sub.p4 A or derivatives thereof from the reaction product if it contains A.sub.p3 A or derivatives thereof.
Japanese Patent Application (OPI) No. 146539/1983 (corresponding to U.S. Pat. No. 4,572,894) (the term "OPI" as used herein means an unexamined published Japanese patent application) describes use of an aminoacyl-tRNA synthetase as a condensing agent in synthesizing peptide or peptide derivatives from amino acids. Japanese Patent Application (OPI) No. 106296/1984 (corresponding to U.S. Ser. No. 461,308 filed on Jan. 26, 1983 and European Patent No. 84975) describes use of one enzyme for converting AMP to ADP and one enzyme for converting ADP to ATP in combination for producing ATP from AMP, the resulting ATP then being used to synthesize a physiologically active substance. These descriptions, however, are not directed to the synthesis of diadenosine tetraphosphate or derivatives thereof.